1. Field of the Invention
The present invention relates to a process for preparing an aminopropylalkoxysilane from a hydrosilane compound and an allylamine compound. More particularly, the present invention relates to a process for the preparation of an aminopropylalkoxysilane in which the reaction is carried out in the presence of a phosphorus compound having a phosphorus-nitrogen bond and a rhodium compound.
2. Description of the Related Art
The present invention relates to a process for preparing an aminopropylalkoxysilane, to improve the adhesive force between an inorganic filler or substrate and an organic resin, for example, between a glass and a a plastic material.
A .gamma.-aminopropyltrialkoxysilane is conventionally prepared by adding a trialkoxysilane to acrylonitrile and hydrogenating the nitrile group to form an amine, but according to this process, the yield in the hydrogenation of the nitrile is low, and therefore, the product is expensive.
An aminopropyltrialkoxysilane also can be synthesized by adding a trialkoxysilane to allylamine, and since the reaction is a one-stage reaction, the aminopropyltrialkoxysilane can be prepared at a low cost. Nevertheless, the reaction between allylamine and a trialkoxysilane, forms a .beta.-aminopropyltrialkoxysilane as a by-product, although only a .gamma.-compound is formed if the synthesis reaction is carried out between acrylonitrile and a trialkoxysilane.
Since the object of the present invention is to obtain an aminopropylalkoxysilane which is a .gamma.-compound, it is necessary to control the formation of the .beta.-compound as the by-product to as low a level as possible. A platinum type catalyst is known as the catalyst for the reaction between allylamine and hydrosilane, but if the platinum type catalyst is used, not only the desired .gamma.-compound but also 6% of the .beta.-compound as the by-product is formed by the addition reaction (see the specification of U.S. Pat. No. 4,481,364). As the means for controlling the formation of the .beta.-compound as the by-product, a method has been proposed of using a rhodium-triorganic phosphorus complex catalyst (see U.S. Pat. No. 4,556,722). The triorganic phosphorus is defined as a compound in which each organic residue is bonded by a single valency to the phosphorus atom through a carbon atom or an oxygen atom of an aliphatic ether.
According to this known method, the formation of the .beta.-compound as the by-product can be controlled, but the control effect is still too low. Further, a large quantity of the triorganic phosphorus compound as the catalyst must be used.
A method is also known in which, by using a rhodium-carbonyl complex as the catalyst, the reaction between allylamine and hydrosilane is promoted while controlling the formation of the .beta.-compound as the by-product (see Japanese Unexamined Patent Publication No. 64-89).
In this method, the .beta.-compound is still formed in an amount of 5 to 6%, and thus a further improvement is desired. The valency of the rhodium metal in the rhodium-carbonyl complex is 0 or negative, and an organic group sucn as triphenylphosphine is not contained as the ligand.